Transcript JBenedict_HIS305_Week3_Teachback2_v01.7b

--------------------------------------------Week Four Teachback: The Artificial Heart and
Contact Lenses
Joel Benedict
University of Advancing Technology
HIS305-D09OCT16
Professor Josh Miller
Introduction

A heartbeat and a blink happen in a microsecond thousands
of times every day. While a blink is necessary for sight, a
heartbeat is necessary for survival. This presentation shows
the societal implications upon life and life quality brought
by the invention of artificial hearts and contact lenses.
Artificial hearts introduced the old medical concept of triage
into a new societal context. Contact lenses introduced
artificially perfected sight invisible to all but the wearer.
The first blood pump
The artificial heart has started and stopped over
its one hundred and twenty year history, but
feasibility of a self-contained apparatus could
only be imagined with a workable blood
pump. William W.L. Glenn, M.D. was “most
fortunate” to work with William H. Sewell, Jr.,
M.D. to create a heart pump as a bypass: “I do
not know when he first got the idea that he
wanted to build an artificial heart. It is likely
this was when he entered medical school and
perceived a practical use for his mechanical
skills. He told me that as a child he often
played with an Erector set his father bought
him” (Glenn, 1993).
The first blood pump cont'd
Sewell constructed a single bypass pump from household items
and a children’s toy. Sewell and Glenn found the test dogs
healthy after the pump test: “That it was possible to bypass
one side of the heart with a mechanical pump for a
prolonged period with survival of the animal and that the
chamber of the right ventricle could be exposed long enough
for deliberate performance of a cardiac operation under
visual control had been demonstrated” (Glenn).
Legacy of the blood pump
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1964 saw the first use of a nearly identical pump in an
operation on a patient.
Modern versions of the centrifugal Bio-Pump invented by
Harold Kletschka in 1975 are still sold and are in use for
biventricular support in 2009 (Oransky, 2004).
Artificial heart valves
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Development towards a True Artificial Heart (TAH) was
incrementally iterative. Each new technology had a separate
application to a specific problem.
The blood pump served to circulate blood, and the artificial
heart valve served as a circulation gateway.
Hydraulic engineer
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Albert Starr and the Edwards Development Laboratory
developed the valve alongside financier M. Lowell Edwards:
“background was in hydraulic engineering, and he designed
many hydraulic debarking systems for the lumber industry. He
had many patents, the most important of which was his fuelinjection system for rapidly climbing aircraft during World War
II. [… ] His interests in fluid dynamics was now directed to the
human circulation” (Starr, 2007).
Success of AHV
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A whole kennel of dogs died in 1958 from the first valves,
but when one survived, so the experiment survived.
In 1960, the second patient survived the surgery and lived a
normal life for more than nine years afterwards.
Legacy of valve replacement
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“Valve replacement became a frequent procedure, with
a fall in operative morality from 50% to zero in the first
six years” (Starr). By the 1990s, a tissue substitute
replaced the synthetic valve materials and made valve
repair surgeries an almost routine procedure. Valve
replacement had a high success rate from initial
surgeries.
The first TAH bridge to transplant
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Development of a TAH was a
more complex task with more
complex equipment.
A 1969 surgery installed an
internal TAH as a bridge to
receipt of a heart transplant, but
the patient died soon after from
multiple organ failures
(Smithsonian, 2009).
Complications
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In 1991 and up to present day, complications are still
present: “Short-term and long-term pnuematic and
centrifugal unilateral and bilateral assist devices and total
artificial hearts have complications of thrombosis, sepsis,
bleeding, and hemolysis, and it is not entirely clear which
will be the limiting factor in these devices” (NHLBI, 1991,
p. 220).
Limitation factors on the TAH patient also exist, in the form
of mobility and mortal longevity.
Development of TAH
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An energy source is required for every
assistive machinery or TAH. The 2001
AbioCor featured electrical
conductivity from beneath the skin
and reduces risk of sepsis infections,
whereas pneumatic internal devices
require a hole in the thoracic skin.
1974 ended propositions for nuclear
powered devices (NHLBI, p. 207).
Despite complications, breakthroughs
came gradually, initiated by the first
bridge to transplant in 1978, and
continued by a fifty four hour bridge
to transplant in 1981 (NHLBI, p. 208).
The first destination TAH
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The Jarvik-7 implant into Barney Clark in 1982 was a left
ventricular assist device (VAD), a stage of innovation in
between a TAH and a Bio-Pump. Clark was already
critically ill prior to surgery. Clark suffered from multiple
organ complications suffered while in a hospital for 112
days (Sandeep, 2004). Until 1990, few TAHs were used, but
VADs saw widespread use.
Major TAH deployment
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“On July 2, 2001, the first fully contained
artificial heart was implanted in a 58-yearold man at Jewish Hospital in Louisville,
Kentucky” (Sandeep). The hydraulically
powered Ambiocor device has been
implanted in at least thirteen patients.
As of 31 October, 2009, “there have been
more than 800 implants of the [SynCardia]
Total Artificial Heart, accounting for more
than 170 patient years of life on the device”
(SynCardia, 2009). The SynCardia is not
used in the U.S.
Intended usage
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The devices are a destination, but not a substitute for a
transplant.
TAHs give patients an average of six months and double life
expectancy, enough time to get affairs in order.
Societal impacts
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The primary use of VADs is as a bridge, which leaves the
TAH with a selective, terminally ill group of patients.
Yet the selection of patients is limited by expense and
complications. There are more eligible patients for TAHs
than there are resources.
Not every patient is qualified for a VAD bridge to
transplant. The result is triage. Society faces an old medical
challenge, but one that is rendered inert in other areas.
Impact on innovation and perspective
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Social acceptance and demand for TAHs led to research and
development for other organs (Koford, 2004). The artificial
kidney was invented, went through a triage period, and
finally achieved social acclimation as a common, widely
available piece of medical equipment.
While TAH and TAK are critical sustainers of life, survival
has not yet taken priority over quality of life. The TAH may
offer a momentary reprieve from death, but given a choice
between survival and the quality of life offered by contact
lenses, the importance of TAH takes precedence.
The first widely influential contact lenses
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The history of contact lens idea
conception goes back further than the
1936 use of polymethyl methacrylate
(PMMA) and the 1888 glass lenses,
but contact lenses did not start to see a
societal impact until soft lenses were
created in 1971: “Thus, PMMA
haptics fom the late 1930s and then
flat Tuohy and contour PMMA lenses
dominated the contact lens field until
hydrogel contact lenses became
available in about 1971” (Bennett,
2005, p.4).
Innovations in lens materials
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The soft hydrogel lenses were comfortable enough for daily
wear up to thirty days, but made the eye swell overnight due
to oxygen deprivation of the cornea.
As a result, by 1984, rigid-gas-permeable (RGP) contact
lenses were still used more often than hydrogel lenses due to
the higher oxygen and moisture levels in rigid lenses.
By 1991, soft silicone lenses had the highest gas
transmission of the three types (Flattau, 1991, p. 8).
“Corneal oxygenation during the wear of rigid contact
lenses occurs both by passage of oxygen through the lens
material itself and by introduction of oxygen containing
tears beneath the lens during blinking” (Patterson, 1999).
Adoption of contact lenses
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The development and manufacture of contact lenses has
always been a group effort. Silicone elastomers in 1981 and
silicone hydrogel in 1998 were developed by large
multinational corporations (Bennett, p.1).
Disposable lenses debuted in 1984 and were reinvented and
commercialized by Johnson & Johnson in 1988 (Bennett, p.
9).
The disposable silicone hydrogel was inexpensive and
comfortable enough to cement the contact lens as a
replacement for glasses for an entire society: “nearly 35
million persons in the United States and 85 million or more
worldwide wear contact lenses” (Bennett, p.10).
Societal impact of contact lenses
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Contact lenses are plentiful and widely available. The
societal impact of contact lenses is more than correction of
vision.
Lenses do not break in the same way glasses do, thus are
safer for sports and are more replaceable than glasses.
Lenses give a complete field of view lacked by glasses.
Normal corrective contact lenses do not obstruct the face as
glasses do. Contact lenses invisibly raise quality of life.
Conclusion
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Contact lenses show the elevation of
quality of life that a medical and
social invention should ideally
accomplish. While the TAH is not the
permanent correction that contact
lenses are, it gives a form of life and a
crucial iteration toward a curative
solution. The future of the heart beat
will be determined by the creative
visions of inventors.
References 1 of 4
Bennett, E.S., Weissman, B.A. (2005). Clinical contact lens
practice.Philadelphia, PA: Lippincott Williams & Wilkins.
Retrieved 31 October, 2009 from http://bit.ly/1bvXaH
Flattau, P.E. (ed.). (1991). Considerations in contact lens use
under adverse conditions: proceedings of a symposium. ,
D.C.: National Academy Press. Retrieved 31 October, 2009
from http://bit.ly/1VDoNd
Glenn, W.W.L. (Winter 1993). Sewell’s pump. The Guthrie
Journal, 1(63). Whitney Museum. Retrieved 30 October,
2009 from http://bit.ly/3lvsF
References 2 of 4
Koford, J.K. (2004). High technology in the healing arena: A
history of the artificial kidney, 1913--1972.Ph.D.
dissertation. Utah: The University of Utah. Retrieved
October 31, 2009, from ProQuest Dissertations & Theses:
Full Text.
Sandeep Jauhar. (2004). The Artificial Heart. Boston, MA: The
New England Journal of Medicine, 350(6), 542-4. Retrieved
October 31, 2009, from Research Library Core.
NHLBI, Hogness, J.R., VanAntwerp, M. (1991). The artificial
heart: prototypes, policies, and patients. Washington, D.C.:
National Academy Press. Retrieved 30 October, 2009 from
http://bit.ly/UcayK
References 3 of 4
Oransky, I. (8 May, 2004). Obituary: Harold
Kletschka.London, UK: The Lancet. Retrieved 8 October,
2009 from http://bit.ly/3ySJ8w
Patterson, H.A. (1999). The effects of rigid contact lens center
thickness, material transmissibility, and blinking on oxygen
shortfall of the human cornea. , OH: Ohio State University
Press. Retrieved 31 October, 2009 from
http://rave.ohiolink.edu/etdc/view?acc_num=osu1159556692
Smithsonian. (2009). Treasures of American history: human
machines.Washington, D.C.: Smithsonian Institution
National Museum of American History Kenneth E. Behring
Center. Retrieved October 30, 2009 from
http://bit.ly/3WrLrK
References 4 of 4
Starr, A. (2007). The artificial heart valve.Lasker Foundation.
Retrieved 30 October, 2009 from
http://www.laskerfoundation.org/awards/pdf/2007_c_starr.pd
f
SynCardia Systems, Inc. (July 2009). 800th implant of world's
only approved total artificial heart performed by heart and
diabetes center NRW in Hospital Business Week
(135).Retrieved from http://bit.ly/12bBH3